"Suppose that you are an expert user of Windows NT/XP/Vista/7, an expert user of an iPad, and an expert user of an Android phone," wrote Greenspun, a computer scientist who teaches at MIT, "you will have no idea how to use Windows 8."

Windows 8 lacks consistent "back" and "home" buttons that make tablet experiences work, and "integrates the tablet and the standard Windows desktop in the most inconvenient and inconsistent possible way," Greenspun opined, adding: "The only device that I can remember being as confused by is the BlackBerry PlayBook."

In a side note at the bottom, Greenspun theorized that tech writers have given Windows 8 decent reviews because "journalists love anything new, different, and complicated. Windows 8 is all of those things."